code: def get_gcs_client(self) -> luigi.contrib.gcs.GCSClient:
      if self._client is None:  # use cache as like singleton object
          self._client = self._get_gcs_client()
      return self._client
  
file_path: gokart/gokart/gcs_config.py
imports: import json
  import os
  import luigi
  import luigi.contrib.gcs
  from google.oauth2.service_account import Credentials
label_desc: Use image node_id 1 for calling the GCSConfig obj's underlying member method code with example usage: obj.get_gcs_client() and returns: self